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AdV-DET (Commissioning)
gouaty - 10:57 Friday 18 October 2019 (47273) Print this report
OMC lock trouble shooting

This morning the OMC1 lock acquisition was failing because the OMC2 was resonant as the same time as OMC1 (see attached figure). Thus when reaching a resonance on OMC1, the power on the B1 photodiodes was reaching 3 mW, which (as expected) triggered the safety closing the fast shutter.

I reduced the temperature of OMC2 from 23.326 to 23.314°c and the OMC2 is no longer resonant at the same time as OMC1.

Images attached to this report
Comments to this report:
gouaty, mwas - 11:42 Friday 18 October 2019 (47274) Print this report

Michal has updated the OMC node in METATRON to improve the logic concerning the setting of the OMC2 initial temperature.

Previously, the OMC2 temperature set in the ini file was updated only after locking OMC2, but not in the case only OMC1 was locked. Thus in case of a modification of the locking temperature of OMC1, this was not propagated to OMC2, which could lead with some bad luck, to having the OMC2 resonant at the same time as OMC1.

Now when the OMC1 is locked, the OMC2 temperature will be updated in the ini file, by the same delta T as the change of OMC1 temperature. This should reduce the odd of having the two cavities resonant at the same time.

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